1. Technical Field
The present invention relates to semiconductor fabrication and more particularly to high k/metal gate devices and methods for fabricating the same having tuned p-type field effect transistors.
2. Description of the Related Art
In conventional high dielectric constant (high-K) metal gate (HK/MG) fin field effect transistors (FET), a p-type FET (pFET) usually exhibits a threshold voltage (Vt) that is higher than a target value. Forming a thin layer in a channel may be effective to lower planar pFET Vt. However, when a layer is grown on finFET sidewalls, the total fin width increases, degrading electrostatics of the finFET. For example, even 5 nm of growth on each side of a 10 nm fin results in the final width of 20 nm which is unacceptable for 22 nm nodes and beyond. Therefore, there is a need for tuning pMOS finFET without compromising device performance.